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From: Arnd Bergmann <arnd.bergmann@de.ibm.com>
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Subject: Re: [PATCH 03/44 take 2] [UBI] user-space API header
Date: Tue, 20 Feb 2007 14:17:40 +0100
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On Tuesday 20 February 2007 14:07, Artem Bityutskiy wrote:
> 
> > This structure is not suitable for an ioctl call, because it has
> > incompatible layout between 32 and 64 bit processes. The easiest
> > fix for this would be to change the 'name' field to an array
> > instead of a pointer.
> 
> Will be fixed thanks. Just out of curiosity, could you please provide an
> example when this may be a problem.

On a 64 bit process with a 32 bit user app calling this ioctl, the kernel
would read the pointer value from the 8 bytes at the end, which means that
it will read four bytes after the end of the structure and interpret
whatever it finds as a pointer, instead of using only the first four
bytes as the lower half.

	Arnd <><